@inputkit/core

Framework-agnostic utilities for formatted inputs. Card type detection, Luhn validation, formatters, and validators — no React, no DOM.

Usage

import {
  formatCardNumber,
  detectCardType,
  validateCardNumber,
  validateLuhn,
  formatExpiry,
  stripNonDigits,
} from "@inputkit/core";

// Format a card number with auto-detected gaps
formatCardNumber("4111111111111111");
// => "4111 1111 1111 1111"

// Amex gets 4-6-5 grouping automatically
formatCardNumber("378282246310005");
// => "3782 822463 10005"

// Detect the brand from a partial number
const type = detectCardType("37");
// => { brand: "amex", displayName: "American Express", ... }

// Validate with Luhn, length, and type checks
validateCardNumber("4111111111111111");
// => undefined (valid)

validateCardNumber("4111111111111112");
// => "Card number is invalid"

// Format an expiry date
formatExpiry("1225", { prevValue: "", action: "insert" });
// => "12 / 25"

// Use Luhn directly
validateLuhn("4111111111111111");
// => true

Custom card types

import { createCardTypeRegistry } from "@inputkit/core";

const registry = createCardTypeRegistry([
  {
    brand: "store-card",
    displayName: "My Store Card",
    startPattern: /^999/,
    lengths: [16],
    gaps: [4, 8, 12],
    code: { name: "PIN", length: 4 },
  },
]);

registry.detect("9991234567890123");
// => { brand: "store-card", ... }